Toggle the visibility of the textures by clicking on the check boxes in the list of textures at the top.

To improve the quality of the model, in the Properties viewport >> Object modifiers >> increase the Multiresolution modifer Preview setting from 8 to 9 or 10

Discussion about textures

The textures for this tutorial came from Koordinates. I used QGIS to export them as bitmaps. The colour map was created procedurally from the heightmap, the rest were from vector outlines of roads, land parcels, and buildings. This method works, but it is not the only method, nor is it neccesarily the best method. To be more efficient with RAM and CPU it would be prudent to merge the textures using a programme such as GIMP. Also, use a texture size that has dimensions that are a power of 2, such as 64x64. 128x128, 256x256, 512x512, 1024x1024, 2048x2048, 4096x4096. For more depth, check out the Blender documentation on Image Textures.